Hi 411A
all the diatribe about CDA being somehow 'safer' is nonsense.
Would you consider it "safer" to fly an ILS by ignoring the glide path and diving to the "LOC only MDA", fly level to your MAP and then Land?
The dear old TriStar is still my favourite of all I've flown. CAT IIIB 75m No DH in the 1970s - PFM.
But if our modern NAV FMS is able to generate a pseudo "glide path" for our NPA (VNAV, FINAL APP or whatever it's called) as vertical guidance then we can use the published DA on the procedure. If we can't generate vertical guidance (LNAV, NAV only) then we use MDA limits. (+ 50 for us)